Digital receivers for low-frequency radio telescopes UTR-2, URAN, GURT

This paper describes digital radio astronomical receivers used for decameter and meter wavelength observations. This paper describes digital radio astronomical receivers used for decameter and meter wavelength observations. Since 1998, digital receivers performing on-the-fly dynamic spectrum calculations or waveform data recording without data loss have been used at the UTR-2 radio telescope, the URAN VLBI system, and the GURT new generation radio telescope. Here we detail these receivers developed for operation in the strong interference environment that prevails in the decameter wavelength range. Data collected with these receivers allowed us to discover numerous radio astronomical objects and phenomena at low frequencies, a summary of which is also presented.Comment: 24 pages, 15 figure

ANGULAR STRUCTURE OF FRII RADIO SOURCES 3C169.1 AND 3C263 AT DECAMETER WAVELENGTHS

The radio galaxy 3C169.1 and the quasar 3C263, located at nearly the same distance with red shift z>0.6, have similar morphological and spectral characteristics. The maps of the sources obtained at decimeter and centimeter wavelengths have shown they are FRII radio sources with steep spectra and approximately equal angular sizes. The very first investigation of the sources structure at decameter wavelengths is presented in the report. Observations were made using a network of the URAN decameter interferometers with baselines 42 to950 km and with maximum angular resolution of arcsec order of magnitude. The models of the image of these sources based on visibility functions measured have been obtained at frequencies of 20 and 25 MHz. They were composed of elliptical components with Gaussian brightness distribution. To facilitate the comparison of these lowfrequency models with high-frequency radio images, the latter were converted to the similar models by fitting the Gaussian components to lobes and hot spots selected at the maps. Comparison of the models revealed changes in a structure of the sources caused by the frequency decrease.

SEARCH FOR THE THIRD HARMONIC OF TYPE III BURSTS RADIO EMISSION AT DECAMETER WAVELENGTHS

The results of observations of trio bursts consisting of type III bursts are presented in this paper. The instantaneous frequency ratio of trio components is near 1:2:3. We analyze flow, duration, frequency drift rate and polarization of trio components as well as dependencies of these characteristics on frequency

Polarization of Drifting Pairs at Decameter Waves

International audienc

New decameter radiopolarimeter URAN-2

International audienc

New decameter radiopolarimeter URAN-2

International audienc

New decameter radiopolarimeter URAN-2

International audienc

Multi-antenna observations in the low-frequency radio astronomy of solar system objects and related topics studies. Planetary Radio Emissions|PLANETARY RADIO EMISSIONS VIII 8|

Rapid progress currently takes place in the field of low-frequency radio astronomy in the meter–decameter–hectometer range of wavelengths. It is caused by a radical modernization of the existing radio telescopes, creation of a new generation of instruments, space-borne observations, and by the development of research on all classes of astrophysical objects, including the Solar System. On the other hand, a range of difficulties specific to low-frequency radio astronomy is known, which are caused by technical, methodological, and physical limitations. An effective strategy for overcoming these difficulties is based on synchronous observations using several radio telescopes separated by distances from a few to several thousand kilometers. This provides an opportunity to reduce and identify radio interference and the influence of the propagation media, to increase the sensitivity and resolution, and to solve many problems with higher efficiency. In recent years such simultaneous observations were carried out for the Sun, Jupiter, Saturn, interplanetary medium, pulsars, exoplanets, and transients using the radio telescopes UTR-2, URAN, GURT, NDA, NenuFAR, LOFAR and other. Parallel observations with the space missions WIND, STEREO, Cassini and Juno also facilitate improvement of the quality and reliability of low-frequency radio astronomical experiments